基于粘贴玄武岩纤维布的在役简支钢筋混凝土桥梁性能提升研究

Research on Improving the Performance of In-Service Simple-Supported Reinforced Concrete Bridge Based on BFRP Sheet

钢筋混凝土梁桥在中小跨径中应用较为广泛,经过多年使用后往往处于带裂缝工作状态,尤其是涉水时往往耐久性退化速度较快,进而会引起结构承载能力降低。而玄武岩纤维复合材料(BFRP)具有较高的抗拉强度和良好的耐侵蚀性能,将其粘贴于在役梁的梁底受拉区,既可以起到隔绝空气提高混凝土耐久性的作用,也可以提升在役梁的抗弯能力,以适应不断增长的交通量。以一座经BFRP布粘贴加固的在役简支板桥为研究对象,开展理论分析与基于ABAQUS的精细化数值模拟,通过对比加固前后的受力性能,进而研究BFRP布对在役简支板梁的受力性能的改善效果,并通过试验对加固前后的受力性能提升规律进行了验证。结果表明,BFRP布粘贴在梁底受拉区可以协助板底主筋参与结构受力,使钢筋和混凝土受力重分布,使得裂缝发展程度降低,在一定程度上提升了梁的整体抗弯刚度,加固后桥梁正常使用情况下的变形能力提升20.6%,钢筋应力水平下降23.9%,抗弯承载能力提高26.9%,增强了结构的安全性。

Reinforced concrete beams are more widely used in small and medium span bridges,which are often in the working state with cracks after many years of use,especially when wading water,the durability degradation speed accelerates,and then the bearing capacity of the structure will be reduced.While basalt fiber composite material(BFRP)has high tensile strength and good erosion resistance.Sticking BFRP in the tension area at the bottom of the in-service beam can not only improve the durability of concrete by isolating air,but also improve the bending resistance of the beam in-service to adapt to the increasing traffic load.Taking an in-service simple-supported beam slab bridge strengthened with BFRP sheet as an example,theoretical analysis and refined numerical simulation based on ABAQUS were carried out to study the improvement effect of mechanical performance of BFRP sheets on the simple-supported slab beam by comparing before and after reinforcement,and the improvement law of mechanical performance before and after reinforcement was verified by experiments.As a result,BFRP sheets pasted in the tensile area of the beam could assist the main reinforcement of the plate bottom to participate in structural stress,so that the stress of the steel and concrete were redistributed,and the degree of crack development was reduced,and the overall bending stiffness of the beam was improved to a certain extent.After reinforcement,the deformation capacity of the bridge under normal service condition upgraded by 20.6%,the stress level of the steel reinforcement decreased by 23.9%,and the bending bearing capacity improved by 26.9%,which enhanced the safety of the structure.